Catalytic preparation of soluble poly(dichlorophosphazenes)

ABSTRACT

HIgh molecular weight poly(dihalophosphazenes) which exhibit solubility in benzene and in substituted benzenes are prepared in solution or in bulk from dihalophosphazenes such as (Cl 2  PN) 3   -7  at moderate temperatures by the use of novel polymerization catalysts.

This invention relates to the preparation of poly(dichlorophosphazene)which is soluble in various solvents including benzene, chlorobenzenes,toluene and mixtures of such solvents.

More specifically it relates to the polymerization ofdichlorophosphazene of the formula (Cl₂ PN)₃₋₇ to polymers of theformula [Cl₂ PN]₂₀₋₅₀,000 wherein the polymerization is accomplished insolution or in bulk in the presence of one or more catalysts.

Uncatalyzed bulk polymerization of (Cl₂ PN)₃, (Cl₂ PN)₄, or mixturesthereof, to form soluble [Cl₂ PN]_(n) polymer is described in U.S. Pat.No. 3,370,020. This process employs temperatures of 200°-300° C,preferably about 250° C.

Another known process for producing soluble poly(dichlorophosphazenes)is described in Example 1 of U.S. Pat. No. 3,515,688 and elsewhere inthe literature. This is essentially a batch process in which cyclictrimeric (Cl₂ PN)₃ is heated in a sealed tube under an inert atmospherefor a stated time at polymerizing temperatures.

A simpler process for the large scale production of soluble [Cl₂ PN]_(n)polymer in good yield is desired because this polymer can be convertedto useful phosphazene derivatives as described for example, in recentlyissued U.S. Pat. Nos. 3,370,020; 3,515,688; 3,700,629 and 3,702,833 andelsewhere.

The primary object of this invention is to provide a simple process forthe preparation of soluble, high molecular weight [Cl₂ PN]_(n) polymerat a significantly lower temperature than currently practiced in theart, said polymer having an intrinsic viscosity of about 0.01 to about3.0 dl/g(benzene, 30° C), and a solubility in benzene, toluene, xylene,chlorobenzene and o-dichlorobenzene.

Another object of this invention is to provide novel cyclic phosphazenepolymerization catalysts useful in the above process and a method fortheir preparation.

Still another object of this invention is to form the [Cl₂ PN]_(n)polymer by a process in which the polymer produced is ready for reactionor purification immediately following polymerization, thereby avoidingthe delay normally encountered when high molecular weight materials aredissolved.

These and other objects, which will be apparent from the descriptionwhich follows, are achieved by the use of specific catalysts which makepossible the polymerization of cyclic phosphazene oligomers in solutionor in bulk to form the desired poly(dichlorophosphazene) polymer.

The catalyzed polymerization when conducted in accordance with thisinvention is conducted with ease in solution or in bulk and attemperatures which are significantly lower than those previouslyemployed. The use of lower temperatures result in a more efficientpolymerization and also diminish the tendency to form gel.

For solution or bulk polymerization any convenient pressure can be usedfrom vacuum up to atmospheric pressures and above. Vaporization ofstarting monomer(s) in systems which are not closed, can be repressed byemploying 10 weight % or even less of a suitable solvent. Previouslyreported bulk polymerizations at elevated temperature under atmosphericconditions have been attended by significant vaporization of monomer(s)with concurrent change of monomer(s) to catalyst ratio, conditionsundesirable for reproducibility and molecular weight control. Othergeneral advantages of a solution polymerization process are thatviscosity is more readily controlled and good agitation can beaccomplished in very inexpensive equipment.

Still another important advantage in an atmospheric solutionpolymerization process is that the [Cl₂ PN]_(n) polymer so produced canbe purified immediately or can be utilized directly for subsequentderivatization as in its reaction with alkoxide, fluoroalkoxide, oraryloxide salts, or mixtures thereof.

Other advantages of the polymerization process of this invention willbecome evident when the process is compared with the known art whichrelates to the bulk polymerization of hexachlorophosphazene, (Cl₂ PN)₃,octachlorophosphazene, (Cl₂ PN)₄, and mixtures thereof as described, forexample, in Allcock, "Phosphorus-Nitrogen Compounds", Academic Press,N.Y., 1972 and Chem. Reviews, 72, 315 (1972). The bulk polymerizationsreported in the prior art are conducted under vacuum and have furtherdisadvantages. For example, high temperatures (220°-350° C) arerequired, nonreproducible products are obtained, formation of gelledpolymer (particularly at moderate to high conversions) is experienced,molecular weight is difficult to control, and a product with a highdegree of polydispersity is obtained.

By the polymerization process of this invention the polymerization ofcyclic compounds having the formula (X₂ PN)_(m), where m is a wholepositive integer of from 3 to 7 inclusive and X is a halogen selectedfrom F, Cl, Br and all of the X's are not required to be identical, isaccomplished at temperatures from about 130°-220° C in solution or about130°-200° C in bulk for periods ranging from 1 hour to several days atany suitable pressure between vacuum and superatmospheric pressure.

For solution polymerization the concentration of monomer can vary fromabout 5-95%. Preferred solvents for solution polymerization are thosewhich are unreactive to both catalyst and (X₂ PN)_(m) monomer and whichpreferably are solvent for both monomer and polymer at polymerizationtemperature. Suitable solvents include nitro or halo aromatics such aschlorobenzene, 1,2-dichlorobenzene, 1,2,4-trichlorobenzene,bromobenzene, m- or p-bromochlorobenzene, nitrobenzene, o- orm-nitrotoluene, m-chloronitrobenzene, and mixtures of these solvents.These and other solvents which may also be employed singly or incombination include benzene, biphenyl, toluene, xylene, halogenatedbiphenyls, carbon tetrachloride, hexachloroethane, tetrachloroethane,pentachloroethane, and hexachlorobutadiene. The methylated benzenes arepreferably used at temperatures below 195° C and benzene and biphenylare preferably used at temperatures below 220° C.

When the polymerization is conducted at atmospheric pressure or above, adry inert atmosphere such as nitrogen, helium, or argon is preferablyemployed. Polymerizations may be conducted under vacuum or underpressure. The concentration of catalyst(s) can vary from 0.1-20% but ispreferably in the range of 0.1-5%.

Conversions of up to about 80% of soluble [Cl₂ PN]_(n) polymer have beenachieved wherein the polymer is characterized by an intrinsic viscosityas measured in benzene at 30° C of from about 0.01 to about 3.0 dl/g.High percent conversions to polymer are favored by an increase intemperature, catalyst(s) concentration, monomer concentration, andpolymerization time. The [Cl₂ PN]_(n) polymer so produced ischaracterized by very little or no gelled material and is thus, ideallysuited for the subsequent preparation of other substitutedpolyphosphazenes which have a wide range of utility.

Although polymerizations are preferably carried out with compounds offormula (Cl₂ PN)_(m), polymerization of fluoro-, bromo-, and even mixedhalo- cyclophosphazenes have been effected. In general, the fluoroderivatives require higher polymerization temperatures and the bromoderivatives require lower polymerization temperatures than those used topolymerize the corresponding chloro derivatives.

The catalysts employed in the practice of the polymerization process ofthis invention to form soluble, high molecular weight [Cl₂ PN]_(n)polymer are selected from three groups, namely metal or organo metalsalts derived from very strong acids (Group A), strong acids (Group B),and derivatives of halocyclicphosphazenes (Group C). Catalysts may beemployed singly or in combination.

Representative members from each group include the following:

Group (A): comprises metallic or quaternary ammonium salts in which theanion is selected from the group consisting of: ##STR1## where R₁ is amonovalent member selected from the group consisting of polyhaloalkylwhere the halogen is F, Cl or mixtures thereof, perfluoroaryl andperchloroaryl; R₂ is a monovalent member selected from the groupconsisting of F, Cl, lower alkyl (C₁ -C₅), aryl, substituted alkyl andsubstituted aryl with the proviso that R₂ is not halogen when bonded to##STR2## Z is F or Cl; M is a metal selected from Groups Ia, Ib, IIa,IIb, and VIII of the Periodic Table, Pb, Mn, or Th; r is the valence ofMetal M; t is an integer designating the magnitude of the negativecharge of the complex ion [M^(r) Z_(r) _(+t) ]⁻ ^(t) ; and Q is a metalselected from the group consisting of Hg, Cd and Zn and X' is either Bror I; and x is 0 or 1.

The following are representative as examples of specific catalysts ofGroup (A):

1. Sulfonic acids where R₂ (above) includes the following:

lower alkyl (methyl through butyl)

perfluoromethyl

perfluorophenyl

fluoro-

chloro-

phenyl-

toluoyl-

naphthyl-

p-bromophenyl-

nitrophenyl-

2,4-dinitrophenyl-

biphenyl-

m-(HO₃ S)phenyl-

2. Polyhalocarboxylic acids where R₁ (above) includes the following:

trifluoromethyl-

trichloromethyl-

difluoromethyl-

difluorochloromethyl-

perfluoropropyl-

perfluorobutyl-

3. Salts of miscellaneous acids:

fluoroboric

fluorophosphoric

picric

phosphoric

pyrophosphoric

polyphosphoric

hydriodic (alkali, alkaline earth and quaternary ammonium salts only)

4. Salts where the anion is a complex polyhalide represented by theformula [M^(r) Z_(r) _(+t) ]⁻ ^(t) where M is a metal or nonmetal ionhaving a valence of r and is selected from Al, As, Fe, Mo, V, Nb, Ta,Pd, Pt, Re, Rh, Ti, Zr, Sb, Sn; Z is F or Cl; and t is an integerdesignating the magnitude of the negative charge of said complex ion.Representative complex negative ions are SbF₆ ⁻, SbCl₆ ⁻, AsF₆ ⁻, AlF₆ ⁻³, FeF₆ ⁻ ³, TiF₆ ⁻ ², and MoCl₆ ⁻ ³.

5. Alkaline and alkaline earth salts having an anion represented by theformula [QX'₄ _(-x) ]⁻.sup.(2^(-x)) where x is zero or 1; Q is selectedfrom Hg, Zn, Cd; and X' is bromine or iodine.

Preferred cations for all the catalyst salts of this invention are Li,Na, K, Mg, Ba, Hg, Ag, and quaternary ammonium ions.

Group (B): comprises the strong acids of Group (A), i.e., the sulfonicacids and polyhalocarboxylic acids used to prepare the metal saltcatalysts of Group (A), picric acid, and in addition H₃ PO₄ and thedehydrated derivatives of H₃ PO₄ such as pyrophosphoric acid, P₂ O₅ andP₂ O₅ --H₃ PO₄ mixtures, usually designated "polyphosphoric acid".

Group (C): comprises substituted cyclophosphazenes represented by theformula (X)_(y) (PN)_(m) (An)_(x), where m is a positive integer of 3 to7; x and y are positive integers the sum of which equals 2m; x being atleast one and y being not less than zero; each X is a halogen selectedfrom F, Cl, or Br; An represents an anion described in Group (A) above,and all the An groups need not be identical to other An groups presentin the cyclophosphazene and for cyclophosphazenes containing two or moreX's, all of the X's need not be identical.

The catalysts of Groups A, B, and C may be employed singly, incombination, or as mixtures with non-catalyst metal halide salts such asLiCl, LiBr, MgCl₂, MgBr₂, HgCl₂, HgBr₂, which may be added for thepurpose of modifying the polymerization.

The phosphazene derivatives of Group (C) are prepared by substitutionreactions of X₆ P₃ N₃ or X₈ P₄ N₄, or mixtures thereof, or mixtures withhigher oligomers, wherein X is a halogen as described above, with one ormore of the salts described in Group (A). Preferred cations of the saltare silver, alkali metal, mercury and quaternary ammonium. Theinterchange is accomplished at temperatures from about 25° C to 130° C,or even higher, providing the temperature is such that little or nopolymerization occurs, and reaction times of about 1 hour to severaldays have been used. The reaction is preferably carried out in a drypolar aprotic solvent such as organic ethers [e.g. tetrahydrofuran,1,2-dimethoxyethane, 1,4-dioxane, bis(2-methoxyethyl)ether],alkylnitriles (e.g. CH₃ CN, C₃ H₇ CN), nitroalkanes (e.g. CH₃ NO₂, C₂ H₅NO₂, t-C₄ H₉ NO₂), nitrobenzene and nitrotoluene, and mixtures thereof,but less polar solvents such as benzene, toluene and their ringchlorinated or brominated derivatives may also be employed. Polarsolvents such as N,N-dimethylformamide, N,N-dimethylacetamide,N-methylpyrrolidinone, and hexamethylphosphoramide may also be usedsingly or in combination with the above solvents provided that reactiontemperatures are maintained below 50° C.

The phosphazene derivatives prepared as above described, can be freed ofinsoluble salt and used directly for the solution polymerization processof this invention, provided they are in a suitable solvent forpolymerization, or they may be isolated and then used for polymerizationof halophosphazene oligomers, or mixtures thereof. Isolation andpurification are carried out by methods well known in the art.

The cyclophosphazene derivatives are advantageous as polymerizationcatalysts because they afford homogeneous polymerizations and moreimportantly may afford [Cl₂ PN]_(n) polymer with low polydispersity.

In the polymerization process of this invention monomer, catalyst, andsolvent (if employed), are brought together at an appropriatetemperature under an inert atmosphere. Suitable methods include: (1)prereacting the entire polymerization mixture at a temperature below thedesired polymerization temperature to form in situ a compound of Group(C), and then continue polymerization at the desired polymerizationtemperature; (2) identical to method (1) except there is no separatelyconducted prereaction at a lower temperature; and (3) prereacting alimited amount of monomer, with a salt of Group (A), adding theremainder of monomer, and solvent, if any, and heating at the desiredpolymerization temperature. Incremental additions of catalyst, monomer,or both, may be made in the practice of any of the above polymerizationmethods.

The remarkable catalytic activity shown by the very strong acidsutilized in this invention was unexpected in view of the resultsreported with hydrogen chloride. It has been found that bulkpolymerizations of (Cl₂ PN)₃ in the presence of HCl (≦1-5×10⁻ ³ weight%) at 250°-270° C are not only retarded in rate but afford lowermolecular weight [Cl₂ PN]_(n) polymer than polymerizations conducted inthe absence of HCl, whereas polymerizations using the strong acidcatalysts of this invention have been successfully conducted atconsiderably lower temperatures (150°-190° C). It has been found thatessentially no polymerization occurred when benzoic acid was employedunder conditions which gave significant polymerization with the acidcatalysts of this invention.

Not all strong acids and their salts are active catalysts for thepolymerization of cyclic (Cl₂ PN)₃ to soluble essentially linear [Cl₂PN]_(n) polymer. For example HCl, HBr, HgCl₂ and HgBr₂ are not catalystswhen employed by themselves.

The following examples are not intended to limit the invention in anyway, but are merely exemplary preferred embodiments of this invention.

EXAMPLES 1 - 38

A dry Pyrex test tube (200 × 25 mm) was charged with a stirring bar,catalyst, (Cl₂ PN)₃ monomer (10-20 g, vacuum distilled andrecrystallized from n-heptane), and solvent (50 weight %), unlessindicated otherwise. The reaction mixture was purged with dry nitrogenand heated under N₂ one hour at 150°-155° C prior to reachingpolymerization temperature, unless indicated otherwise. Intrinsicviscosities ([η], dl/g) of soluble polymer were run in dry benzene at30° C and % conversion to polymer was determined by vapor-phase-liquidchromatography. The solvents employed were either (A) a 2:1 (by weight)mixture of 1,2--Cl₂ C₆ H₄ --C₆ H₅ NO₂, (B) 1,2,4--Cl₃ C₆ H₃, or (C)1,2--Cl₂ C₆ H₄. The results are shown in Examples 1-38.

    __________________________________________________________________________         Catalyst (weight                                                                         Solv-                                                                              Polymerization                                           Ex.  % on Monomer)                                                                            ent(s)                                                                             Conditions   Remarks                                     __________________________________________________________________________                         ° C                                                                          Hrs.                                               1    None       A    190   15     No Polymer                                  2    (CF.sub.3 SO.sub.3).sub.2 Hg[1%]                                                         B    217    3     Soluble polymer                                                               [η] = 1.4                               3    (CF.sub.3 SO.sub.3).sub.2 Hg[1%]                                                         A    190    6 1/2 Soluble Polymer                             4    (CF.sub.3 SO.sub.3).sub.2 Hg[1%]                                                         C    190   10     Soluble polymer                             5    (CF.sub.3 SO.sub.3).sub.2 Hg(0.3%)                                                       B    217    3     Soluble polymer                                             (75%)             [η] = 2.7                               6    CF.sub.3 SO.sub.3 Ag(1%)                                                                 A    190    6 1/2 Soluble and                                                                   gelled polymer                              7    AgPF.sub.6 (3%)                                                                          A    190    7     Soluble polymer,                                                              low conversion                              8    (C.sub.6 F.sub.5 SO.sub.3).sub.2 Ba(1%)                                                  A    190    4     Soluble polymer                             9    [2,4-(NO.sub.2).sub.2.sup.-                                                              A    190    4     Soluble polymer                                  C.sub.6 H.sub.3 SO.sub.3 ].sub.2 Mn(1%)                                  10   KSbCl.sub.6 (1%)                                                                         A    190    6     Soluble Polymer                             11   CO(BF.sub.4).sub.2 (1%)                                                                  A    190    6     Soluble Polymer                             12   CF.sub.3 CO.sub.2 Ag(2%)                                                                 A    190    6 1/2 12% Conversion,                                                               [η] = 0.20                              13.sup.(b)                                                                         HgI.sub.2 (2%)+                                                                          C    190    7     19% Conversion                                   NaI (0.7%)                                                               14   HgI.sub.2 (2%)+                                                                          C    190   11     2% Conversion                                    NaI(0.7%).sup.(c)            prior to addi-                                                                tion of NaI)                                15   NaI(2%)    C    190   10 1/2 13% Conversion                              16   C.sub.6 H.sub.5 SO.sup.- 3(CH.sub.3).sub.4 N.sup.+                                       A    190   11     51% Conversion,                                  (2%)                         [η] = 0.06                              17   Li.sub.2 TiF.sub.6 (2%)                                                                  A    190    6     25% Conversion -18 CF.sub.3 SO.sub.3                                          Na(2%) A 190 10  10% Conversion             19   (CH.sub.3 SO.sub.3 Hg).sub.2 O(2%)                                                       A    190    2 1/2 61% Conversion                                                                [η] = 0.31                              20   (CH.sub.3 SO.sub.3 Hg).sub. 2 O                                                          A    190   15     24% Conversion                                   (0.5%)                       [η] = 0.75                              21   (CH.sub.3 SO.sub.3 Hg).sub.2 O(2%)                                                       A    150-155                                                                             17 1/2 Soluble Polymer                             22                                                                                  ##STR3##  A    190    2 1/2 40% Conversion                              23   (CH.sub.3 SO.sub.3).sub.2 Zn(2%)                                                         A    190   10     7% Conversion                               24   CH.sub.3 SO.sub.3 H(2%)                                                                  A    190    6 1/2 21% Conversion                              25   CH.sub.3 SO.sub.3 H(2%)+                                                                 A    190    6 1/2 24% Conversion                                   LiCl(1%)                                                                 26   C.sub.6 F.sub.5 CO.sub.2 H(2%)                                                           A    190   40     53% Conversion                              27   CF.sub.3 SO.sub.3 H(2%)                                                                  A    190.sup.(d)                                                                         4      Soluble Polymer                             28   Cl.sub.3 CCO.sub.2 H(2%)                                                                 A    190   8      30% Conversion                              29   n-C.sub.3 F.sub.7 CO.sub.2 H(2%)                                                         A    150-155                                                                             25     15% Conversion                              30   n-C.sub.7 F.sub.15 CO.sub.2 H(2%)                                                        A    190   13     36% Conversion                              31   P.sub.2 O.sub. 5 (2%)                                                                    A    190   26     63% Conversion,                                                               [η] = 0.24                              32   polyphosphoric                                                                           A    190   23     47% Conversion,                                  acid (2%)                    [η] = 0.55                              33   polyphosphoric                                                                           C    190   24     43% Conversion                                   acid (2%)             30     60% Conversion,                                                               [η] = 0.15                              34   polyphosphoric                                                                           C    190   24     15% Conversion                                   acid (2%) +                                                                   LiCl (2%)                                                                35   KNCS(2%)   A    190   25     40% Conversion,                                                               [η] = 0.25                              36   picric acid(2%)                                                                          A    190   10     Soluble Polymer                             37   ClSO.sub.3 H                                                                             A    190   6      Soluble Polymer                             38.sup.(e)                                                                         (CF.sub.3 SO.sub.3).sub.2 Hg (2%)                                                        C.sub.6 H.sub.6                                                                    200   24     Soluble Polymer                                             (90%)                                                         __________________________________________________________________________     .sup.(a) Derivatized to [(CF.sub.3 CH.sub.2 O).sub.2 PN(HC.sub.4 F.sub.8      CH.sub.2 O).sub.2 PN] by reaction with an equimolar mixture of CF.sub.3       CH.sub.2 ONa and HC.sub.4 F.sub.8 CH.sub.2 ON.sub.a, [η] 30°       acetone = 1.0 dl/g. Calcd: C, 23.5; H, 1.7; Cl, 0.0. Found: C, 22.2; H,       1.5; Cl, 0.1.                                                                 .sup.(b) NaHgI.sub.3 and Na.sub.2 HgI.sub.4 formed in situ.                   .sup.(c) Added 11 hours after addition of HgI.sub.2. Gelled polymer forme     101/2  hours after addition of NaI.                                           .sup.(d) Reaction heated 18 hours at 150° C prior to heating to        reflux.                                                                       .sup.(e) Polymerization conducted in sealed tube under pressure.         

EXAMPLES 39-42

The procedure of Example 1 was followed using the indicated monomer(s)and (CH₃ SO₃ Hg)₂ O (2% on monomer) as catalyst and 1,2-Cl₂ C₆ H₄ -C₆ H₅NO₂ (2w/1w) as solvents (50% concentration) at 190° C.

    __________________________________________________________________________         Monomer     Polymerization                                               Ex.  (% by weight)                                                                             Time (Hours)                                                                          Remarks                                              __________________________________________________________________________    (Cl.sub.2 PN).sub.3                                                                      (Cl.sub.2 PN).sub.4                                                39   25    25     4      27% Conversion,                                                               [η] = 0.10                                       40.sup.(a)                                                                         25    25    111/2   46% Conversion,                                                               [η] = 0.07                                       41    0    50    43      19% Conversion                                       42   30    15    111/2   40% Conversion                                       + 5% mixture of                                                               (Cl.sub.2 PN).sub.5, (Cl.sub.2 PN).sub.6                                      __________________________________________________________________________     .sup.(a) LiCl(2%) present with the (CH.sub.3 SO.sub.3 Hg).sub.2 O             catalyst.                                                                

EXAMPLES 43-50

The procedure of Example 1 was followed without any solvent.Polymerizations of Examples 43-50 were conducted in a sealed evacuatedpyrex tube.

    __________________________________________________________________________       Catalyst                                                                      (weight % on                                                                             Polymerization                                                  Ex.                                                                              monomer)   Conditions                                                                             Remarks                                                __________________________________________________________________________                  ° C                                                                          Hrs.                                                      43 None       217   3  No high polymer                                        44 (CF.sub.3 SO.sub.3).sub.2 Hg(3%)                                                         230-240                                                                             3  Gelled polymer                                         45 (CF.sub.3 SO.sub.3).sub.2 Hg(0.5%)                                                       190   5  Soluble polymer                                        46 CF.sub.3 SO.sub.3 Ag(1%)                                                                 180   3  Soluble polymer                                        47 HgCl.sub.2 (1%)                                                                          250   8  24% Conversion,                                                               [η].sub..sub.φH.sup.30.sup.° C =                               0.46 dl/g                                              48 HgBr.sub.2 (1%)                                                                          250   8  29% Conversion,                                                               [η].sub..sub.φH.sup.30.sup.° C =                               0.52 dl/g                                              49 HCl        190   24 No high polymer                                        50 polyphosphoric(1%)                                                                       190   20 Soluble polymer                                        __________________________________________________________________________

EXAMPLE 51

A 1-liter flask was charged under a nitrogen atmosphere with (Cl₂ PN)₃(450g), o-dichlorobenzene (50 g), and polyphosphoric acid (3.0 g,Matheson Coleman & Bell Company). The mixture was heated with goodagitation 1 hour at 150°-170° C and then at about 195° C for 45 hours togive a very viscous mixture. Unreacted (Cl₂ PN)₃ was removed byextracting twice with 500 ml dry heptane, and then by stirring overnightat 40° C with 500 ml dry petroleum ether. Solvent was decanted off andthe [Cl₂ PN]_(n) polymer (184 g, 41% yield), which had an intrinsicviscosity of 0.9 dl/g (benzene, 30° C), was dissolved in 500 ml drybenzene. This polymer solution was reacted with an equimolar mixture ofCF₃ CH₂ ONa and HCF₂ C₃ F₆ CH₂ ONa in tetrahydrofuran for 1 day at roomtemperature to give, after purification, an elastomericpoly(fluoroalkoxyphosphazene) copolymer with an inrinsic viscosity 1.1dl/g in acetone (30° C) and a chlorine content of 0.03%.

EXAMPLES 52-53 Polymerization of (Cl₂ PN)₃ Using Phosphazene CatalystExample 52: Via (Cl₂ PN)₃

The phosphazene catalyst was prepared by reaction, under dry nitrogen,of (Cl₂ PN)₃ (3.0 g), (CH₃ SO₃ Hg)₂ O (0.5 g), in nitrobenzene (7.5 g)for 4 hours at 135° C. The mixture was cooled to room temperature andinsoluble solids removed by centrifuging. An aliquot (4.0 g) of theclear yellow liquor was added to (Cl₂ PN)₃ (13.8 g) and 1,2-Cl₂ C₆ H₄/C₆ H₅ NO₂ (2w/1w, 12.2 g) which was polymerized under nitrogen for 61/2hours at 190° C. The [Cl₂ PN]_(n) polymer which was produced (53%yield by vapor-phase-liquid chromatography) had an intrinsic viscosityof 0.40 dl/g (benzene, 30° C).

EXAMPLE 53: Via (Cl₂ PN)₄

The phosphazene catalyst was prepared by reaction, under dry nitrogen,of (Cl₂ PN)₄ (3.0 g, 6.5 mmol), CF₃ CO₂ Ag (4.0 g, 18.0 mmol) innitrobenzene (18 g) for 2 hours at 75° C. The immobile mass was shakenwith 1,2-Cl₂ C₆ H₄ (36 g) and solids removed by subsequent centrifuging.An aliguot (7.5 g) of the clear light yellow solution was added Cl₂ PN)₃(15 g) and 1,2-Cl₂ C₆ H₄ /C₆ H₅ NO₂ (2w/1W, 7.5 g) which was polymerizedunder nitrogen for 6 hours at 190° C. The [Cl₂ PN]_(n) polymer which wasproduced (29% yield) had an intrinsic viscosity of 0.22 dl/g (benzene30° C).

EXAMPLE 54

A mixture of (CH₃ SO₃ Hg)₂ O (0.3 g), (Cl₂ PN)₃ (1.0 g), andnitrobenzene (5.0 g) was heated under nitrogen with stirring at 135° Cfor 2 hours. Vapor-phase-liquid chromatography was indicative of asignificant change in (Cl₂ PN)₃ concentration. The mixture was added toadditional (Cl₂ PN)₃ (14.0 g) and o-dichlorobenzene and heated at gentlereflux (Ca.190° C) for 4 hours. Soluble polymer (33% conversion) wasformed which had an intrinsic viscosity of 0.10 dl/g (benzene, 30° C).

EXAMPLE 55 Preparation of a Poly(chloro-trifluoroacetoxy)Cyclophosphazene

To a solution of (Cl₂ PN)₃ (2.5 g, 7.19 mmol) in dry tetrahydrofuran (50ml) was added, with good stirring under nitrogen, silvertrifluoroacetate (5.0 g, 22.6 mmol). The reaction was covered withaluminum foil, stirred 18 hours at room temperature and refluxed 4hours. The mixture was cooled, centrifuged, liquor removed, and solidsreslurred with tetrahydrofuran (40 ml) and centrifuged. The combinedclear liquor was evaporated under vacuum and then dried to constantweight under high vacuum. A whitish semi-solid mixture [4.1 g, theoryfor (Cl)₃ (CF₃ CO₂)₃ P₃ N₃ is 4.19 g]was obtained. The tetrahydrofuraninsoluble solids were washed with acetone and dried to give 3.25 g.Further treatment of this solid with 15% HNO₃ (60 ml) (CF₃ CO₂ Ag isinsoluble in this acid) followed by washing with water and methanolgave, after vacuum drying, 3.14 g (theory = 3.24 g for AgCl). Thesoluble semi-solid showed several significant volatile components invapor-phase-liquid chromatography indicative of a mixture ofpoly(chloro-trifluoroacetoxy) cyclophosphazenes.

EXAMPLE 56 Preparation of (CH₃ SO₃ Hg)₂ O

A flask was charged with methanol (500 ml), HgO (108 g, 0.50 mol); andCH₃ SO₃ H (101 g, 0.57 mol) and stirred well under reflux for 2 hours.Methanol (150 ml) was removed by distillation and benzene (200 ml) wasadded. The mixture was concentrated to about 1/2 the volume and amixture of isopropyl alcohol (150 ml) and benzene (250 ml) was added.The mixture was cooled, solid filtered off and washed with isopropylalcohol-benzene (1v/1v) and vacuum dried at 130° C for 18 hours. Theproduct (141 g, 93% yield) was obtained as a whitish solid. Anal. Calcd.for (CH₃ SO₃ Hg)₂ O: C, 4.0; H, 1.0; S, 10.5 Found: C, 4.1; H, 1.0; S,10.7. Anal. Calcd. for (CH₃ SO₃ Hg)₂ O: C, 6.1; H, 1.5; S, 16.4.

We claim:
 1. A process for the preparation of solublepolyhalophosphazene polymer consisting essentially of recurringstructural units represented by the formula [X₂ PN] and having anintrinsic viscosity of about 0.01 to about 3.0 dl/g (benzene, 30° C),said polymer being soluble in benzene, toluene, chlorobenzene, anddichlorobenzene, which comprises heating at least one cyclic oligomerrepresented by the formula (X₂ PN)_(m) where m is 3-7, wherein X is ahalogen selected from the group consisting of F, Cl, and Br and all ofthe X's are not required to be identical, at temperatures of about 130°C to 220° C in the presence of an effective amount of at least onecatalyst which is selected from the group consisting of A and B andmixtures thereof wherein:Group A consists of metallic or quaternaryammonium salts in which the anion is represented by one of the followingformulae: ##STR4## where R₁ is a monovalent member selected from thegroup consisting of polyhaloalkyl, where the halogen is F, Cl ormixtures thereof, perfluoroaryl and perchloroaryl; R₂ is a monovalentmember selected from the group consisting of F, Cl, lower alkyl (C₁-C₅), aryl, substituted alkyl and substituted aryl with the proviso thatR₂ is not halogen when bonded to ##STR5## and the metal of the salt is ametal selected from the group consisting of Li, Na, K, Mg, Ba, Hg, Ag,Mn and Zn; Group B consists of at least one acid selected from the groupconsisting of acids represented by the following formulae: ##STR6## H₃PO₄ and its dehydrated derivatives and wherein R₁ and R₂ are as definedin Group A.
 2. The process of claim 1 wherein the polymerization iscarried out in a solvent.
 3. The process of claim 2 in which the solventis selected from the group consisting of benzene, chlorobenzene,o-dichlorobenzene, 1,2,4-trichlorobenzene, and mixtures thereof.
 4. Theprocess of claim 1 which including in addition the step of heating thereactants and catalyst to a temperature significantly below thepolymerization temperature prior to raising the temperature to effectpolymerization.
 5. The process of claim 1 in which a dehydratedderivative of H₃ PO₄ is employed as catalyst.
 6. The process of claim 1in which the polymerization is effected in the presence of an alkali oralkaline earth chloride or bromide and the polymerization catalyst is H₃PO₄ or dehydrated derivative of H₃ PO₄.
 7. The process of claim 1wherein the concentration of catalyst is between 0.1% and 20%.
 8. Theprocess of claim 1 wherein the initial concentration of monomer isbetween 5 and 95%.
 9. The process of claim 1 wherein the polymerizationis effected in the temperature range from 130° C to 220° C.